1. Field of the Invention
The present inventions relates to the field of security devices and more specifically to the area of key locks.
2. Description of the Prior Art
Recently, several concepts have been patented in which a conventional tumbler actuating key is combined with an auxiliary coding mechanism in order to provide a higher degree of security by increasing the number of codes beyond those available on conventional tumbler actuated keys.
In U.S. Pat. No. 4,200,227, a conventional tumbler actuating key is described as containing a coded electrical circuit that is responsive to short wave radiation. The circuit is embedded within a plastic assembly that is welded or otherwise bonded to the key handle so that the electrical circuit is isolated away from the surface of the key.
In U.S. Pat. No. 4,298,792, a conventional key is shown as containing a coded track along its shank. The key is shown to contain a single code track composed of alternating light and dark fields that are read by sensors in the vicinity of the receiving aperture of the lock. The sensors read the track as the key is inserted into the lock.
In U.S. Pat. No. 4,366,466, the use of a conventional key is described, which additionally includes a housing for a data carrier. The data carrier is described as containing information on, for example, a recording tape, a recording wire, an optically scannable medium or other conventional medium. The data carrier is further said to include either an unerasable portion containing data reflecting vehicle-related information or an erasable portion containing arbitrary information.